The invention discloses a method for calculating a metering error of an electric energy meter. The method comprises the following steps: controlling a three-phase power source to generate three analog voltage signals and three analog current signals according to set test point requirements; setting the proportion of a three-phase AC proportion standard, and converting the voltage signals and the current signals into six voltage small signals; synchronously performing data collection on the six voltage small signals by using 6 high-precision voltage samplers and on output pulses of a to-be-tested electric energy meter by using a universal counter; calculating a standard electric energy value according to data collected by the 6 high-precision voltage samplers, and calculating an electric energy value of the to-be-tested electric energy meter according to the data collected by the universal counter; and calculating the metering error of the to-be-tested electric energy meter according to the standard electric energy value and the electric energy value of the to-be-tested electric energy meter. According to the method disclosed by the invention, the same path of voltage small signals is collected by using the high-precision voltage samplers and the to-be-tested electric energy meter, the error of a standard signal converter is not introduced, and the accurate measurement of the metering error of the electric energy meter can be realized.